My mother lived alone for many years, and as a result, had a rather zen thing about eating. In the summer, dinner was a salad. Greens, crunchy bits, chick peas, maybe some feta. In the winter, it was garbage pail soup. She'd make a big vat of vegetable soup, starting with chicken stock and adding whatever was lingering in the freezer, a handful of lentils or maybe some beans, a parmesan rind if one was at hand, and a spoonful of pesto at the table. No recipe, just instinct. Mind you, I'm not going to say that it was great soup, but it was warm and cheap and healthy.
I kind of love Martha Rose Shulman. She does these columns on the New York Times website, where she'll dive into something and give you four or five semi-variants. Recently, she did gratins, Not Your Grandmother’s Gratin:
Potato and Sorrel Gratin
Roasted Squash and Red Onion Gratin
Fennel, Kale and Rice Gratin
Roasted Cauliflower Gratin With Tomatoes and Goat Cheese
Roasted Eggplant and Red Pepper Gratin
After skimming through all of those recipes, it occurred to me that they were all, at core, the same: vegetables and a grain/starch plus eggs, milk, cheese.
So I sautéed an onion, boiled and sliced a few tired potatoes, added a bag of frozen Swiss chard/beet greens (from last summer's CSA), added a cup of cooked wild rice, mixed it all together and dumped it in an oiled baking dish. I then added 3 eggs beaten up with 1/2 cup milk and some salt and pepper, sprinkled some grated cheddar on top and threw it in the oven. And it was good.
In other words, don't be afraid to invent.